The present invention relates to an apparatus and method for testing jet engine fuel manifolds and, more particularly, to an apparatus and method for testing the flow distribution in jet engine fuel manifolds.
Modern jet aircraft use turbofan jet engines to generate the thrust that moves the aircraft on the ground and through the air. One of the major components of the turbofan engine is the combustor. The combustor receives compressed air from the compression portion of the engine, mixes the air with fuel supplied from fuel injector nozzles, and ignites the fuel/air mixture in a combustion chamber, thereby significantly increasing the energy of the air flowing through the engine. The high-energy air exiting the combustor expands through a turbine, which drives the compressor, and through a nozzle, to provide thrust.
The fuel injector nozzles that supply the fuel to the combustion chamber are coupled to a manifold that is located circumferentially around the engine. If fuel flow through the injector nozzles is uneven, for example if fuel flow through one or more of the fuel injector nozzles is significantly higher than other nozzles, large temperature variations in the hot gas that exits the combustor and impinges upon the turbine will result. These large temperature variations cause unwanted stresses in the turbine, which leads to early replacement of costly turbine components, including the combustors, transition liners, and turbine nozzles.
Uneven fuel flow through the injector nozzles is caused by various defects. For example, if a portion of the manifold, or one or more of the injector nozzles, becomes clogged, then fuel flow through the remaining injector nozzles will be higher than the others. Additionally, after usage one or more of the injector nozzles may wear, resulting in a larger nozzle opening than the other injector nozzles coupled to the manifold.
In order to check for uneven fuel manifold flow distribution, the fuel injector manifolds are periodically removed from the engines and subject to flow distribution testing. Presently, this testing is conducted using one of two known test devices. One of these test devices consists of a test stand that includes one measurement vessel for each injector nozzle. To conduct the test, the fuel manifold and injector nozzles are removed from the engine and are connected to the test stand. A test fluid is then pumped into the manifold and through the injector nozzles, and a predetermined minimum volume of test fluid is collected in each of the individual measurement vessels. After the predetermined volume is collected, test fluid flow is stopped and an operator observes how much fluid is collected in each of the individual measurement vessels. The operator then compares the volumes accumulated from each nozzle and calculates the flow distribution as [(maxxe2x88x92min)/max]xc3x97100, to ensure this is below the limit.
Another known test device also consists of a test stand that includes a measurement vessel for each injector nozzle. However, each of the measurement vessels has a pair of associated optical level sensors. To test a fuel manifold with this device, the fuel manifold and injector nozzles are removed from the engine and are connected to the test stand. A test fluid is then pumped into the manifold and through the injector nozzles, and is collected in each of the individual measurement vessels. As the rising level in each vessel passes the lower optical sensor, a high frequency clock begins counting; as the level reaches the upper optical sensor, the clock stops, and test fluid flow is stopped. A computer determines the flow rate through each of the nozzles based on the time required to fill each vessel to a known volume.
Each of the above-described methods and apparatuses for testing fuel manifold flow distribution has its disadvantages. The first test device and method exhibits a large measurement uncertainty (e.g., +/xe2x88x922% repeatability), due in large part to the operator subjectivity in the measurement and to the coarse graduations of the measuring vessels. This large amount of uncertainty limits the ability of engine maintenance and testing facilities to accurately determine when fuel distribution manifolds are actually exhibiting uneven flow distribution. Although the second test device alleviates the operator subjectivity somewhat, it still suffers numerous disadvantages. For example, the measurement vessels used with this device are opaque and, therefore, do not allow an operator to view the spray pattern of the test fuel as it exits the injector nozzles. In addition, the level sensors used in the device do not provide real-time level sensing and display throughout the test. Thus, an operator will not be able to clearly detect a fault in the system and abort the test, until after the predetermined time period has elapsed. In addition, the device is not configured as a closed loop system, which means that the test fluid pumped through the fuel manifold and into the measurement vessels is not conveniently drained or pumped back to the reservoir from where it originated.
Hence, there is a need for a fuel distribution manifold test device and method that improves upon one or more of the drawbacks identified above. Namely, a device and method that provides increased accuracy and repeatability, and/or provides real-time level sensing and display throughout the test, and/or allows operators to view the fuel nozzle spray patterns during the test, and/or is provided in a closed loop system configuration.
The present invention relates to an apparatus and method for testing the flow distribution through a turbine engine fuel manifold and one or more nozzles connected to the manifold. One embodiment of the present invention allows an operator to view individual measurement vessel levels, view real-time flow data through each of the nozzles, and simultaneously view the fuel nozzle spray patterns throughout the test.
In one aspect of the present invention, an apparatus for testing fluid flow distribution through a turbine engine fuel manifold and one or more fuel nozzles connected thereto includes a test fluid supply tank, one or more test fluid supply lines, a plurality of fluid measurement vessels, a plurality of level sensors, and a computer. The test fluid supply lines each include a test fluid inlet in fluid communication with the test fluid supply tank and a test fluid outlet adapted to be coupled to the fuel manifold and its connected fuel nozzles. The plurality of fluid measurement vessels are each operable to receive a test fluid discharged from one of the fuel nozzles when the fuel manifold is coupled to the test fluid supply line outlet. The plurality of level sensors are individually coupled to each of the fluid measurement vessels and are operable to determine a level of the test fluid therein and generate a level signal representative of the test fluid level. The computer is coupled to the one or more level sensors and is operable to periodically sample each of the generated level signals and calculate test fluid flow rate through each of the fuel nozzles based on the sampled level signals.
In another aspect of the present invention, a method of testing fluid flow distribution through a turbine engine fuel manifold and one or more fuel nozzles connected thereto includes supplying a test fluid to the fuel manifold at a predetermined pressure, and collecting the test fluid discharged from each of the fuel nozzles in separate measurement vessels. The volume of test fluid discharged from each of the fuel nozzles is periodically determined until each of the measurement vessels have collected a predetermined volume of the test fluid. The test fluid flow rate through each of the fuel nozzles is periodically calculated based on the periodically determined test fluid discharge volume.
In yet another aspect of the present invention, a computer-readable storage medium containing computer executable code for instructing a computer, which is coupled to a test stand that is configured to test fluid flow distribution through a turbine engine fuel manifold and one or more fuel nozzles, and that includes a plurality of fluid measurement vessels each operable to receive a test fluid discharged from one of the fuel nozzles, to perform the steps of periodically determining and displaying a volume of test fluid discharged from each of the fuel nozzles until each of the measurement vessels have collected a predetermined volume of the test fluid, and periodically calculating and displaying test fluid flow rate through each of the fuel nozzles based on the periodically determined test fluid discharge volume.